Sampling method and apparatus



Dec. 7, 1965 M. A. LAGERGREN SAMPLING METHOD AND APPARATUS Filed May 31, 1963 ATTORNEYS United States Patent O 3,221,558 SAMPLING METHUD AND APPARATUS vMilton A. Lagergren, Salt Lalre City, Utah, assignor to This invention relates to the art of sampling materials, and is particularly concerned with providing a new sampling method and apparatus for taking undisturbed samples of various unconsolidated solid materials having some moisture content, but especially those which are highly moist or actually impregnated with liquid. It was developed primarily for sampling earth materials not susceptible to satisfactory sampling in any other way, for example, metallurgical tailings ponds, lake bottoms, and the like. However, it is useful in a wide variety of instances involving metallurgical and other industrial slurries.

The invention was conceived primarily for use in obtaining undisturbed samples from metallurgical tailings ponds where conventional sampling methods have not proven successful. At one such pond, for example, a vertical open pipe, sharpened on its leading edge, was driven into the tailings in an attempt to force a sample into the pipe. This proved a failure because only a small increment of material entered the pipe; the bulk of the material was pushed ahead.

Next, an auger was used to bore approximately two feet ahead of a casing driven into the tailings as the sampling progressed. This method proved very time consuming, and the sample obtained, although satisfactory for some purposes, was disturbed and failed to indicate the dividing line between the tailings deposit and underlying river sands. Knowledge of this dividing line is necessary for proper determinations of the volume and speed of migration of metallurgical values to the ground beneath.

A third and faster method employing a rotary drill Was used for the majority of samplings. Compressed air was used at the drill bit to blow cuttings out of each hole as it was deepened. The samples obtained were disturbed and not very reliable, because the cuttings tended to plaster the hole above the hit, some sloughing of the hole walls occurred, and the dividing line between the tailings and the river bottom could not be determined. None of the methods and apparatus tried resulted in a sample from which bulk density, water content, pH, metallurgical content of the water in th soil, and compaction could be determined.

Although developed primarily to overcome the inherent deficiencies of methods and apparatus previously used in obtaining sample-s of tailings deposits composed mainly of very fluid materials overlying soft silty type materials that are underlain by a harder, more impervious layer which prevents rapid drainage and drying out of the upper materials, the invention also has utility in the obtaining of samples of other materials. Thus, the invention has utiilty for the sampling of a Wide range of natural soils, where there is sufficient moisture present to act as a binder when frozen, of various industrial slurries, and of other materials composed of or containing freezable liquid.

Accordingly, it is a principal object of the present invention to provide for the taking of continuous and undisturbed samples of various materials, especially moist, unconsolidated, solid materials, for the entire depth penetrated. Such a sample clearly indicates the various strata encountered and clearly indicates each interface between different strata, for example, the interface between different types of solid materials and between solid material and standing water thereabove.

A further object of the invention is to provide sampling apparatus that can be used to obtain a continuous, undisturbed, sample of unconsolidated materials, without changing the volume or dissolved mineral content of free water in the sample.

In achieving the foregoing objects, a hollow sampling vessel, preferably of elongate tubular formation, is inserted into the material to be sampled, to the desired depth, and the temperature in such sampler is reduced to below the freezing point of the liquid concerned, thereby freezing the liquid component of a surrounding portion of such material to be sampled and causing the relative positions of the solids and liquid contained in such portion to remain fixed, and to firmly adhere to the sampler. Thereupon, the sampler and adherent sample are withdrawn, without disturbance of the sample. Such sample may then be examined, photographed, tested or otherwise dealt with as desired, all without disturbance thereof so long as it remains frozen.

Testing of the frozen sample can be performed by cutting and removing portions. Inasmuch as the layer of material immediately adjacent the sampler may be disturbed during sinking, it is normally discarded and not used for testing purposes.

The sampler developed for use in carrying out the method of the invention includes an elongate hollow casing, closed at its bottom end and adapted to have a cooling medium applied through its upper end into the hollow section. To facilitate sinking of the sampler, the closed lower end is preferably pointed, and, to facilitate withdrawal, means are preferably provided to equalize pressures above and below the sampler during withdrawal operations.

There are shown in the accompanying drawing certain specific embodiments of the invention representing what are presently regarded as the best modes of carrying out the generic concepts in actual practice. From the detailed description of these presently preferred forms of the invention, other more specific objects and features will become apparent.

In the drawing:

FIG. 1 is a view in elevation and partly in vertical section showing representative structure used in the sinking of one form of sampler in a natural earth area in accordance with the invention;

FIG. 2, an axial vertical section showing the sampler of FIG. 1 as it appears following the freezing of a sample, but prior to its extraction from the earth area;

FIG. 3, a similar vertical section showing a different embodiment of the sampler as extracted from an earth area with the frozen sample adherent thereto; and

FIG. 4, a horizontal cross-section taken on line 44 of FIG. 3.

Referring .to the drawing:

In the illustrated preferred constructions, the sampler shown generally at 10 includes a hollow elongate vessel 11 which may be of any desired cross-sectional configuration.

The closed bottom of vessel 11 preferably has a pointed nose piece 12, and means are provided to allow cooling of the inside of the vessel. Any conventional means, such as the illustrated representative driving means 13, may be utilized to drive the sampler the desired depth into the material to be tested.

In the embodiment shown in FIG. 2, the means provided to cool the inside of vessel 11 includes a refrigerant inlet pipe 14 extending from a refrigerant source, not shown, through top 15, into vessel 11, and terminating at a point adjacent the closed bottom. A refrigerant outlet 16 extends through vessel 11 at a point near top 15 to continuously circulate refrigerant from the vessel back to the refrigerant source.

A vacuum relief tube 17 extends from outside vessel 11 at a point near top 15 and through the vessel and nose piece 12. A pivoted valve 13 is mounted with its pivot 19 below the end of tube 17 so that sinking movement of the nose piece into the material to be tested will force the valve to close the passage, whereas during withdrawal the valve will be opened under the infiuence of gravity and any pressure differential which may develop on opposite sides of the valve.

In operation, vessel 11 and nose piece 12 are driven or otherwise positioned a desired distance into waterbearing material to be tested, and refrigerant is circulated through inlet pipe 14, vessel 11, and outlet 16 to cool the inside of the vessel. This cooling will freeze any adjacent free water that may be present above and in the material adjacent the sampler, thus causing the relative position of the adjacent solids to remain fixed, and the sample to adhere to the sampler.

Withdrawal of the sampler will bring with it the frozen adhering sample 11a, which can then be tested as desired.

In the embodiment of the device shown in FIG. 3, elongate vessel 11 is closed at its bottom end, preferably with a pointed nose 12, as in the previous embodiment. Also as in the previous embodiment, a vacuum relief tube and pivoted valve may be provided, if desired.

After sinking operations, the driving cap (if one is used) is removed from the end of the vessel opposite the nose piece and the vessel end left completely open. The vessel is then filled with Dry Ice 20 and a good con-ducting liquid such as alcohol 21, to lower the temperature in the vessel, and freeze the water in the surrounding sample 11a.

To facilitate raising the sampler, a bail 22 may be provided.

The sample 11a obtained using either the embodiment of the sampler shown in FIG. 2 or the embodiment of FIG. 3 is substantially undisturbed, with only a layer of solids immediately proximate the vessel being disturbed. In testing the sample, it may be desirable to cut a channel section 1112 for the entire length of the sample, or for an intermediate length corresponding to the depth range of particular concern. The layer of material immediately proximate the vessel would normally be dis-carded, since as previously noted it may be disturbed during sinking operations.

Various tests can be made of the material sampled in accordance with the invention, and the particular information sought will dictate whether it is best to test when the moisture therein is still frozen or after it has thawed. Tests that can be easily made include, for example, determinations of bulk density, moisture content, pH, particle size, compaction, and determinations of the kind and amount of dissolved minerals in the water.

Whereas there is here illustrated and specifically described a certain preferred procedure and construction of apparatus which is presently regarded as the best 4 mode of carrying out the invention, it should be understood that various changes may be made and other constructions adopted without departing from the inventive subject matter particularly pointed out and claimed herebelow.

I claim:

I. A method of obtaining an undisturbed sample of moisture-bearing material comprising the steps of: sinking a hollow sampler into said material a desired depth; reducing the temperature within said sampler until the water in a section of material surrounding the sampler is frozen, the relative positions of the solid particles therein are fixed, and the sample adheres to said sampler; and withdrawing the sampler with the adhering sample.

2. The method of claim 1, wherein Dry Ice and a conducting liquid are placed in the sampler to reduce the temperature.

3. The method of claim 1, wherein a refrigerant is circulated through the interior of the sampler to reduce the temperature therein.

4. A sampler for obtaining samples of water-bearing materials comprising: a hollow vessel; a pointed nose piece closing a bottom end of said vessel; and an open top at another end of said vessel through which Dry Ice and a conducting liquid can be inserted into the hollow vessel; and a vacuum relief conduit having one end open to atmosphere at a point adjacent said open top and extend-ing through said vessel and said nose piece; and a valve mounted on said nose piece and adapted to close the other end of said conduit during sinking of said sampler and to open during withdrawal of said sampler.

5. A sampler for obtaining undisturbed samples of fluid-bearing soils comprising: a hollow vessel closed at one end; a refrigerant inlet conduit extending into said vessel at another end and terminating at a point in said vessel adjacent said closed end; a refrigerant outlet conduit connected to the vessel adjacent said end through which the inlet conduit extends, whereby refrigerant is circulated through said inlet conduit, the vessel and the outlet conduit; a vacuum relief conduit having one end open to atmosphere at a point adjacent the end of the vessel through which said inlet conduit passes, said conduit extending through the vessel and the closed end; and a valve positioned to close the other end of the conduit during sinking of said sampler and to open during withdrawal of the sampler.

References Cited by the Examiner UNITED STATES PATENTS 2,331,227 10/ 1943 Proudlock 73425.2 2,865,204 12/1958 Lamb 73-425 LOUIS R. PRINCE, Primary Examiner.

RICHARD QUEISSER, Examiner. 

1. A METHOD OF OBTAINING AN UNDISTURBED SAMPLE OF MOSITURE-BEARING MATERIAL COMPRISING THE STEPS OF: SINKING A HOLLOW SAMPLER INTO SAID MATERIAL A DESIRED DEPTH; REDUCING THE TEMPERATURE WITHIN SAID SAMPLER UNTIL THE WATER IN A SECTION OF MATERIAL SURROUNDING THE SAMPLER IS FROZEN, THE RELATIVE POSITIONS OF THE SOLID PARTICLES 